Tendon injuries in the hand are mostly open, with more cuts, often combined with neurovascular injuries or bone and joint injuries, and closed lacerations may also occur. After the tendon ruptures, the corresponding joints lose their mobility. For example, if the superficial flexor tendon of the finger is ruptured, the proximal interphalangeal joint of the corresponding finger cannot flex; if the deep flexor tendon of the finger is ruptured, the distal interphalangeal joint cannot flex; if both the deep and superficial flexor tendons of the finger are ruptured, both the proximal and distal interphalangeal joints cannot flex. Since the intrinsic muscles of the hand are still intact, the flexion of the metacarpophalangeal joint is not affected. If the extensor tendons are ruptured at different locations, the corresponding joints cannot stretch and may become deformed.